Temperature-Insensitive Second-Harmonic Generation at 0.5321 µm in YCa4O(BO3)3

YCa 4 O(BO 3 ) 3 has been found to have the phase-matching points where the temperature variation of the phase-matching angle (dθ obs /d T ) becomes zero for type-1 second-harmonic generation at 0.5321 µm at θ=30.8° and φ=180°. We also found that the temperature sensitivity of the phase-matching angle in the z x plane differs between the φ=0° and φ=180° propagation directions in this material. In addition, the thermo-optic dispersion formula of YCa 4 O(BO 3 ) 3 is presented.